THERAPEUTIC FOCUSING ULTRASOUND TRANSDUCER

Abstract

This study performed at the intersection of two areas: engineering and biomedical, which
resulted in the development of a therapeutic focusing ultrasound transducer designed for the detection
and non-invasive treatment of neoplasms. Main principle is emitting high-intensity ultrasonic
vibrations into the focus spot (High Intensity Focused Ultrasound – HIFU). This allows to
target selected areas and perform ablation of inflamed or foreign tissues without open surgery.
Based on the characteristics of piezoceramic materials produced in the "Piezopribor" SCTB,
mathematical modeling of the HIFU converter was performed. The basis is a piezoceramic element
made in the form of a thin-walled segment of a sphere with a central hole, made of ferroelectric
material PCP-35. The central hole with a diameter of 41.4 mm is designed for the imaging
sensor, which acts as a" gunner" of a focused ultrasonic beam. The principle of operation of the
transducer is as follows: the focal spot with the maximum acoustic pressure is located in the area
captured by the ultrasound-compatible sensor. The image is transmitted to the monitor, after
which a decision is made on which areas and with what intensity to influence the ultrasonic transducer.
The amplitude-frequency characteristics of the converter are studied. The dependences of
the active conductivity on the frequency in the free and water-loaded states are obtained. Acoustic
pressure levels in the focus spot were measured. Diagrams of the radiation intensity distribution in
the plane and in three-dimensional space were constructed, and work was carried out on the effect
of an ultrasonic transducer on various organic materials and tissues: organic glass with a thickness
of 10 mm, chicken muscle tissue. The dependences of the impact force on the power supplied
to the converter, as well as the frequency of the master signal, are obtained. The possibility of
using the converter as part of the HIFU therapy complex is experimentally shown. Conclusions
about the prospects of using single-element focusing ultrasonic transducers and multi-element
ones with a distributed focus spot are formulated.